Final answer:
George III slammed the door on all hope of reconciliation with the American colonies by refusing to negotiate and taking aggressive actions. The Conciliatory Proposition offered some concessions, but fell short of colonial expectations. This ultimately led to war.
Step-by-step explanation:
George III slammed the door on all hope of reconciliation by refusing to negotiate with the colonists. In early 1775, Lord North, the Prime Minister, presented a Conciliatory Proposition, which offered some concessions to the Americans, such as imposing trade regulations instead of taxes and allowing the colonists to assume partial responsibility for their own defense. However, these terms fell short of meeting colonial expectations. Additionally, George III declared that Massachusetts was in rebellion and took aggressive actions against the colonists. These actions, along with the unsatisfactory response to the Conciliatory Proposition, ultimately led to the escalation of hostilities and the declaration of war on the colonies.